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A Lean proving system with no extra training proved 669 of 672 Putnam problems and all six IMO 2026 formalizations

AspireAI community · arXiv (cs.CL / cs.AI)
EasyProver puts recursive agents with isolated contexts, asynchronous search and parallel tactic probing in front of an off-the-shelf frontier model, and reports 669/672 PutnamBench problems solved, all six IMO 2026 formalizations, 597/600 NTP4VC verification conditions and all 189 VERINA tasks, by proof or refutation. Because those benchmarks are near saturation, the authors also built Aegis, which turns competitive programming problems into harder verification tasks over real Rust implementations: 2,045 differentially validated Rust-Lean pairs and 11,533 candidate specifications, with 52.7 percent of a 2,000-statement stratified sample proved inside a 30-minute per-statement budget. The honest limit: that 52.7 percent is well short of saturation, and the new benchmark is machine-generated, so it measures a narrower notion of correctness than hand-written ones.
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One distance function matched sparse-autoencoder features across layers and compressed feature circuits into supernodes
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